def add(a, b):
    """Addition function."""
    return a + b

def subtract(a, b):
    """Subtraction function."""
    return a - b

def multiply(a, b):
    """Multiplication function."""
    return a * b

def divide(a, b):
    """Division function."""
    if b == 0:
        return "Error: Division by zero!"
    else:
        return a / b

def main():
    print("Welcome to Simple Calculator!")
    print("1. Addition")
    print("2. Subtraction")
    print("3. Multiplication")
    print("4. Division")
    
    choice = input("Enter choice (1/2/3/4): ")

    num1 = float(input("Enter first number: "))
    num2 = float(input("Enter second number: "))

    if choice == 1:
        print("Result:", round(add(num1, num2),2))
    elif choice == 2:
        print("Result:", subtract(num1, num2))
    elif choice == 3:
        print("Result:", multiply(num1, num2))
    elif choice == 4:
        print("Result:", divide(num1, num2))
    else:
        print("Invalid input!")
main ()
